Security device
First Claim
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1. A security device for electrical appliances, each said appliance deriving input from an external source electrically connected to said electrical appliance by a conductor, said security device comprising:
- encoder-transmitter includinginput means for receiving and storing a predetermined security code;
encoding means for scanning said input means to find said stored code, and upon finding said code, receiving and encoding said code to a suitable data signal;
modulating means for receiving and mixing said data signal onto a modulated carrier for continuous transmission; and
transmitting means for continuously transmitting said modulated carrier on the conductor;
at least one receiver-decoder coupled to said electrical appliance, said receiver-decoder including receiving means connected to the conductor for continuously receiving said modulated carrier;
demodulating means for reconverting said modulated carrier to the data signal by demodulating said data signal out of said modulated carrier;
decoding means for receiving said data signal and comparing said data signal to a normal mode code so as to indicate at least one of the following (a) said data signal matches said normal mode code, (b) said data signal is different than said normal mode code, or (c) said data signal is missing from said modulated carrier; and
said modulating means comprises;
a fixed frequency oscillator for providing a frequency for said carrier;
a variable frequency oscillator for providing a frequency associated with the conductor; and
a mixer connected to both oscillators for mixing said two frequencies and for generating said modulated carrier.
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Abstract
A security device for an electrical appliance which derives input from an electrically connected external source, the device comprising a receiver-decoder which is adapted and arranged to allow the appliance to operate in its normal mode when the receiver-decoder receives a predetermined code carried via the external source and not to allow the appliance to operate in its normal mode when the predetermined code is not received.
93 Citations
12 Claims
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1. A security device for electrical appliances, each said appliance deriving input from an external source electrically connected to said electrical appliance by a conductor, said security device comprising:
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encoder-transmitter including input means for receiving and storing a predetermined security code; encoding means for scanning said input means to find said stored code, and upon finding said code, receiving and encoding said code to a suitable data signal; modulating means for receiving and mixing said data signal onto a modulated carrier for continuous transmission; and transmitting means for continuously transmitting said modulated carrier on the conductor; at least one receiver-decoder coupled to said electrical appliance, said receiver-decoder including receiving means connected to the conductor for continuously receiving said modulated carrier; demodulating means for reconverting said modulated carrier to the data signal by demodulating said data signal out of said modulated carrier; decoding means for receiving said data signal and comparing said data signal to a normal mode code so as to indicate at least one of the following (a) said data signal matches said normal mode code, (b) said data signal is different than said normal mode code, or (c) said data signal is missing from said modulated carrier; and said modulating means comprises; a fixed frequency oscillator for providing a frequency for said carrier; a variable frequency oscillator for providing a frequency associated with the conductor; and a mixer connected to both oscillators for mixing said two frequencies and for generating said modulated carrier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A security device for electrical appliances, each said appliance deriving input from an external source electrically connected to said electrical appliance by a conductor, said security device comprising:
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encoder-transmitter including input means for receiving and storing a predetermined security code; encoding means for scanning said input means to find said stored code and, upon finding said code, receiving and encoding said code to a suitable signal; modulating means for receiving and mixing said data signal onto a modulated carrier for continuous transmission; and transmitting means for continuously transmitting said modulated carrier on the conductor; at least one receiver-decoder coupled to said electrical appliance, said receiver-decoder including receiving means connected to the conductor for continuously receiving said modulated carrier; demodulating means for reconverting said modulated carrier to said data signal by demodulating said data signal out of said modulated carrier; decoding means for receiving said data signal and comparing said data signal to a normal mode code so as to indicate at least one of the following (a) said data signal matches said normal mode code, (b) said data signal is different than said normal mode code, or (c) said data signal is missing from said modulated carrier; and said receiving means comprises; isolating means for passing said modulated carrier while blocking power also associated with the conductor; transformer means connected to said isolating means for isolating power conductors; a low pass filter connected to said transformer for attenuating all signals above a predetermined frequency; and a band pass filter for removing undesired noise from said modulated carrier.
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Specification